Sure! Here's a simple Gun Game in 3D implemented as a single HTML file using JavaScript:
To play the game, open the above code in a web browser on your smartphone (or any device with a web browser) and interact with the game by moving your finger on the screen to control the player and tapping on the screen to shoot the targets. The objective is to hit as many targets as possible and increase your score.
Please note that this is a simple example and can be further enhanced and expanded based on specific game requirements.